[Exact] Comparison between CB, CC, CE Configuration of BJT

Bipolar Junction Transistor(BJT) has a total of three terminals that are Emitter, Base, and Collector. So when a BJT is to be connected in a circuit, it's one terminal that must be taken as the common terminal for both input and output. So, according to taking common terminal, there are three types of configurations that are Common Emitter or CE configuration, Common Base or CB configuration, and Common Collector or CC configuration.

These three transistor configurations have their own characteristics, advantages, and applications. So, let's go to know the comparison between CB, CC, and CE configuration and their characteristics, and applications.

Comparison between CB, CE, and CC Configuration

Characteristics	CB	CE	CC
Common Terminal for Input and Output	Base Terminal	Emitter Terminal	Collector Terminal
Input voltage applied between	Emitter and Base terminal	Base and Emitter Terminal	Base and Collector Terminal
Output Voltage taken across	Collector and Base Terminal	Collector and Emitter Terminal	Emitter and Collector Terminal
Input Impedance	Very Low(only 50 to 500 ohm)	Medium(500 to 5000 ohm)	Very high(200 to 750 kilo ohm)
Output Impedance	Very High(1 to 10 Mega Ohm)	Medium(50 to 500 kilo ohm)	Very Low( up to 50 ohm)
Input Current	Emitter Current or IE	Base Current or IB	Base Current or IB
Output Current	Collector Current or IC	Collector Current or IC	Emitter Current or IE
Output Signal Phase	Same phase with input	180 degree out of phase	Same phase with input
Current Gain	Always less than Unity α = IC/IE	Between 35 to 500 β = IC/IB	Very High γ = IE/IB
Voltage Gain	About 150	About 500	Less Than Unity
Leakage Current	Very Small	Very Large	Very Large
Power Gain	Medium	High	Medium
Application	High Frequency Circuits	RF Signal Processing	Switching Circuits

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CB configuration of Transistor

In this configuration, the base terminal of the transistor is taken as the common terminal. Also, the Base terminal is connected to the ground. In this configuration, the input voltage is applied between the emitter and base terminal. And the output voltage is taken across the collector and base terminal. Here you can see the diagram below.

Characteristics of CB Configuration

1. This configuration provides very low input impedance(only 50 to 500 ohm).

2. It provides very high output impedance(1 to 10 Mega Ohm).

3. In this configuration, the current gain is denoted by alpha(α) which is always less than unity(0.95 to 0.99).

4. In this configuration the output signal is always in the same phase as the input signal.

Application of CB configuration

1. Transistor CB configuration used in current-to-voltage converter circuits.

2. This configuration is used in very high-frequency applications.

3. This configuration is used to increase the impedance of the current source.

Read Also: Why NPN Transistors are mostly used than PNP Transistors?

CE configuration of Transistor

In this configuration, the emitter terminal of the transistor is taken as the common terminal. And the emitter terminal is connected to the ground also. The input voltage is applied between the Base and Emitter terminal and the output voltage is taken across the collector and emitter terminal. Here you can see the diagram below.

Characteristics of CE configuration

1. This configuration provides medium input impedance(500 ohm to 5000 ohm).

2. It provides very high output impedance(50 to 500 kilo Ohm)

3. In this configuration, the current gain is denoted by beta(β) which varies between 35 to 500

4. In this configuration, the phase difference between the output and input signal is 180 degrees out of phase.

Application of CE configuration

1. CE configuration is used RF signal processing circuits.

2. This configuration is used for audio amplifier circuits.

3. This configuration is used in sensor controller circuits.

Read Also: Main Difference Between MOSFET and BJT

CC configuration of Transistor

This is the most usable and simple configuration of transistors. In this configuration, the collector terminal of the transistor is used as a common terminal. And the Collector terminal is connected to the ground also. The input voltage is applied between the Base and Collector terminal and the output voltage is taken across the emitter and collector terminal. Here you can see the diagram below.

Characteristics of CC Configuration

1. This configuration provides very high input impedance(200 to 750 kilo Ohm).

2. It provides very low output impedance(up to 50 Ohm).

3. In this configuration, the current gain is denoted by gamma(γ) which is very high.

4. In this configuration, the output signal is always in the same phase as the input signal.

Application of CC Configuration

1. Transistor CC configuration is used for switching purposes.

2. This configuration is used for impedance matching.

3. This configuration is used in power amplifier circuits.

4. This configuration is used to make digital logic gates.

Read Also: Transistor applications explained with examples

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